North Korean leader Kim Jong Un and South Korean President Moon Jae-in are in the middle of a dramatic three-day summit that has featured warm hugs, elaborate musical performances, and throngs of Pyongyang's residents lining the streets to catch a glimpse of the historic moment.

Late Tuesday night, the pageantry turned into actual business as both leaders vowed to improve their fraught relationship and announced an agreement in which Kim offered the concrete stepstoward dismantling his country's nuclear program.

The problem is their agreement is extremely vague — and may actually prove bad news for the United States.